Heretofore, there are widely known a battery system supplying electric energy of a secondary battery to a power source and a battery equipped vehicle equipped with this battery system. The battery system-equipped vehicle may include for example an electric vehicle, a plug-in hybrid car, a hybrid car, a hybrid railway vehicle, etc. Patent Literatures 1 to 3 listed below disclose such battery systems and battery system-equipped vehicles.
An electric propulsion vehicle (a battery system-equipped vehicle) disclosed in Patent Literature 1 is arranged to set the magnitude of initial output of a secondary battery to a magnitude equal to or larger than an output value obtained by adding a decreased amount of output resulting from a memory effect of the subject secondary battery and an allowable decreased amount of output resulting from aged deterioration of the secondary battery to the output value of a motor. When the initial output of the secondary battery is set to a large value as above, even if the secondary battery deteriorates with time or even if the memory effect occurs in the secondary battery, the secondary battery can provide anytime output power as equal as or larger than the set output value of the motor within a performance warranty period. Thus, the motor can always output power at least at the set output value or more. This makes it possible to prevent deterioration in electric efficiency caused when a user excessively presses an accelerator pedal, and also avoid unnecessary replacement of secondary batteries.
An electric vehicle (a battery system-equipped vehicle) disclosed in Patent Literature 2 is arranged to previously set a plurality of charging modes (economy mode, normal mode, and long drive mode) different in maximum capacity ratio depending on charging current and charging time. From those charging modes, a user chooses one having a maximum capacity ratio corresponding to an intended travel distance of a vehicle. The vehicle performs charging to obtain a charging electrical quantity in the chosen charging mode. It is disclosed that such action can avoid the execution of excessive charging according to the charging mode, energy efficiency is not unnecessarily decreased, so that charging can be conducted according to the purpose of use.
A battery system disclosed in Patent Literature 3 includes a discharging control means for stopping discharging when the voltage of a secondary battery becomes lower than a predetermined reference value during discharging of the secondary battery; and a charging control means for stopping charging when the voltage of the secondary battery becomes higher than the predetermined reference value during charging of the secondary battery. This battery system also includes a history estimating means for estimating the history of the secondary battery based on its state. The discharging control means revises the voltage reference value at which discharging is to be stopped to a larger value according to a historical estimated value by the history estimating means. The charging control means revises the voltage reference value at which charging is to be stopped to a smaller value according to the historical estimated value by the history estimating means. It is disclosed that such control conducted to mitigate an increase in capacity degradation ratio of the secondary battery can extend the life of the secondary battery.